The invention pertains to a water demineralization system usually in a single vessel containing multiple beds of ion exchange resins. It pertains particularly to a water demineralization system and method for which beds of cationic resins, anionic resins and mixed cationic and anionic resins are provided in a single vessel in a series flow arrangement, including a method for rapidly regenerating the resin beds.
Demineralization or softening of water to remove minerals such as calcium and magnesium compounds using ion exchange type resins in a single vessel is generally known. For example, U.S. Pat. No. 2,772,236 to Coonradt et al discloses a single vessel demineralizer system containing a series of ion exchange resin beds. U.S. Pat. No. 2,703,313 to Gill discloses a similar single vessel demineralization system adapted to use multiple beds of fine resin particles. U.S. Pat. No. 3,355,018 to Smith discloses a single vessel containing four beds of ion exchange resins connected in continuous series arrangement, but makes no provision for separate regeneration of the resin beds. U.S. Pat. No. 4,159,350 to Jonsson discloses a single vessel demineralizer having an anion bed and a cation bed in series flow arrangement. Also, U.S. Pat. No. 4,263,145 to Wirth discloses a single vessel containing a mixture of anion and cation resins.
Although the prior art has provided some single vessel systems for demineralization of water, further improvements in the demineralization of water including methods for rapid regeneration of the resin beds are needed for providing demineralized water of high quality and at reduced costs, particularly for steam boiler applications.